Frigid Pluto is home to more diverse terrain than expected

CAPE CANAVERAL, Fla. (Reuters) -- The most detailed look at Pluto's surface to date has revealed an unexpected range of mountains, glacial flows, smooth plains and other landscapes, according to studies released on Thursday.

The unprecedented window into the so-called dwarf planet, which orbits the sun like other planets but is smaller, comes via high-resolution photographs from NASA's New Horizons spacecraft. The interplanetary space probe made the first-ever visit to Pluto and its five moons last July.

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Frigid Pluto is home to more diverse terrain than expected

This image of haze layers above Pluto’s limb was taken by the Ralph/Multispectral Visible Imaging Camera (MVIC) on NASA’s New Horizons spacecraft. About 20 haze layers are seen; the layers have been found to typically extend horizontally over hundreds of kilometers, but are not strictly parallel to the surface. For example, scientists note a haze layer about 3 miles (5 kilometers) above the surface (lower left area of the image), which descends to the surface at the right.

(Photo via NASA/JHUAPL/SwRI/Gladstone et al./Science (2016))

New Horizons’ views of the informally named Sputnik Planum on Pluto (top) and the informally named Vulcan Planum on Charon (bottom). The Sputnik Planum strip measures 228 miles (367 kilometers) long, and the Vulcan Planum strip measures 194 miles (312 kilometers) long. Illumination is from the left. The bright, nitrogen-ice plains are defined by a network of crisscrossing troughs. This observation was obtained by the Ralph/Multispectral Visible Imaging Camera (MVIC) at a resolution of 1,050 feet (320 meters) per pixel. The Vulcan Planum view in the bottom panel includes the “moated mountain” Clarke Mons just above the center of the image. The water ice-rich plains display a range of surface textures, from smooth and grooved at left, to pitted and hummocky at right. This observation was obtained by the Long Range Reconnaissance Imager (LORRI) at a resolution of 525 feet (160 meters) per pixel.

(Photo via NASA/JHUAPL/SwRI)

This enhanced color view of Pluto's surface diversity was created by merging Ralph/Multispectral Visible Imaging Camera (MVIC) color imagery (650 meters or 2,132 feet per pixel) with Long Range Reconnaissance Imager panchromatic imagery (230 meters or 755 feet per pixel). At lower right, ancient, heavily cratered terrain is coated with dark, reddish tholins. At upper right, volatile ices filling the informally named Sputnik Planum have modified the surface, creating a chaos-like array of blocky mountains. Volatile ice also occupies a few nearby deep craters, and in some areas the volatile ice is pocked with arrays of small sublimation pits. At left, and across the bottom of the scene, gray-white methane ice deposits modify tectonic ridges, the rims of craters, and north-facing slopes. The scene in this image is 260 miles (420 kilometers) wide and 140 miles (225 kilometers) from top to bottom; north is to the upper left.

(Photo via NASA/JHUAPL/SwRI)

Far in the western hemisphere, scientists on NASA’s New Horizons mission have discovered what looks like a giant “bite mark” on Pluto’s surface. They suspect it may be caused by a process known as sublimation—the transition of a substance from a solid to a gas. The methane ice-rich surface on Pluto may be sublimating away into the atmosphere, exposing a layer of water-ice underneath.

(Photo via NASA/JHUAPL/SwRI)

Far in the western hemisphere, scientists on NASA’s New Horizons mission have discovered what looks like a giant “bite mark” on Pluto’s surface. They suspect it may be caused by a process known as sublimation—the transition of a substance from a solid to a gas. The methane ice-rich surface on Pluto may be sublimating away into the atmosphere, exposing a layer of water-ice underneath.

(Photo via NASA/JHUAPL/SwRI)

A close-up of the canyons on Charon, Pluto's big moon, taken by New Horizons during its close approach to the Pluto system last July. Multiple views taken by New Horizons as it passed by Charon allow stereo measurements of topography, shown in the color-coded version of the image. The scale bar indicates relative elevation.

(Photo via NASA/JHUAPL/SwRI)

The Mountainous Shoreline of Sputnik Planum: In this highest-resolution image from NASA’s New Horizons spacecraft, great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. "The mountains bordering Sputnik Planum are absolutely stunning at this resolution," said New Horizons science team member John Spencer of the Southwest Research Institute. "The new details revealed here, particularly the crumpled ridges in the rubbly material surrounding several of the mountains, reinforce our earlier impression that the mountains are huge ice blocks that have been jostled and tumbled and somehow transported to their present locations." (Photo via NASA/JHUAPL/SwRI)

Pluto’s ‘Badlands’: This highest-resolution image from NASA’s New Horizons spacecraft shows how erosion and faulting have sculpted this portion of Pluto’s icy crust into rugged badlands topography. (Photo via NASA/JHUAPL/SwRI)

Layered Craters and Icy Plains: This highest-resolution image from NASA’s New Horizons spacecraft reveals new details of Pluto’s rugged, icy cratered plains, including layering in the interior walls of many craters. "Impact craters are nature's drill rigs, and the new, highest-resolution pictures of the bigger craters seem to show that Pluto's icy crust, at least in places, is distinctly layered,” said William McKinnon, deputy lead of the New Horizons Geology, Geophysics and Imaging team, from Washington University in St. Louis. "Looking into Pluto’s depths is looking back into geologic time, which will help us piece together Pluto's geological history.” (Photo via NASA/JHUAPL/SwRI)

On approach in July 2015, the cameras on NASA’s New Horizons spacecraft captured Pluto rotating over the course of a full “Pluto day.” The best available images of each side of Pluto taken during approach have been combined to create this view of a full rotation. (Photo via NASA/JHUAPL/SwRI)

New Horizons scientists made this false color image of Pluto using a technique called principal component analysis to highlight the many subtle color differences between Pluto's distinct regions. The image data were collected by the spacecraft’s Ralph/MVIC color camera on July 14 at 11:11 AM UTC, from a range of 22,000 miles (35,000 kilometers). This image was presented by Will Grundy of the New Horizons’ surface composition team on Nov. 9 at the Division for Planetary Sciences (DPS) meeting of the American Astronomical Society (AAS) in National Harbor, Maryland. (Photo via NASA/JHUAPL/SwRI)

In this extended color image of Pluto taken by NASA’s New Horizons spacecraft, rounded and bizarrely textured mountains, informally named the Tartarus Dorsa, rise up along Pluto’s day-night terminator and show intricate but puzzling patterns of blue-gray ridges and reddish material in between. This view, roughly 330 miles (530 kilometers) across, combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC) on July 14, 2015, and resolves details and colors on scales as small as 0.8 miles (1.3 kilometers). (Photo via NASA/JHUAPL/SwRI)

High-resolution images of Pluto taken by NASA’s New Horizons spacecraft just before closest approach on July 14, 2015, reveal features as small as 270 yards (250 meters) across, from craters to faulted mountain blocks, to the textured surface of the vast basin informally called Sputnik Planum. Enhanced color has been added from the global color image. This image is about 330 miles (530 kilometers) across. For optimal viewing, zoom in on the image on a larger screen. (Photo via NASA/JHUAPL/SwRI)

High-resolution images of Pluto taken by NASA’s New Horizons spacecraft just before closest approach on July 14, 2015, are the sharpest images to date of Pluto’s varied terrain—revealing details down to scales of 270 meters. In this 75-mile (120-kilometer) section of the taken from the larger, high-resolution mosaic above, the textured surface of the plain surrounds two isolated ice mountains. (Photo via NASA/JHUAPL/SwRI)

Pluto’s Majestic Mountains, Frozen Plains and Foggy Hazes: Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. The smooth expanse of the informally named icy plain Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. To the right, east of Sputnik, rougher terrain is cut by apparent glaciers. The backlighting highlights over a dozen layers of haze in Pluto’s tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 780 miles (1,250 kilometers) wide. (Photo via NASA/JHUAPL/SwRI)

Majestic Mountains and Frozen Plains: Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. The smooth expanse of the informally named Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. The backlighting highlights more than a dozen layers of haze in Pluto’s tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 230 miles (380 kilometers) across. (Photo via NASA/JHUAPL/SwRI)

Near-Surface Haze or Fog on Pluto: In this small section of the larger crescent image of Pluto, taken by NASA’s New Horizons just 15 minutes after the spacecraft’s closest approach on July 14, 2015, the setting sun illuminates a fog or near-surface haze, which is cut by the parallel shadows of many local hills and small mountains. The image was taken from a distance of 11,000 miles (18,000 kilometers), and the width of the image is 115 miles (185 kilometers). (Photo via NASA/JHUAPL/SwRI)

Pluto’s ‘Heart’: Sputnik Planum is the informal name of the smooth, light-bulb shaped region on the left of this composite of several New Horizons images of Pluto. The brilliantly white upland region to the right may be coated by nitrogen ice that has been transported through the atmosphere from the surface of Sputnik Planum, and deposited on these uplands. The box shows the location of the glacier detail images below. (Photo via NASA/JHUAPL/SwRI)

Valley Glaciers on Pluto: Ice (probably frozen nitrogen) that appears to have accumulated on the uplands on the right side of this 390-mile (630-kilometer) wide image is draining from Pluto’s mountains onto the informally named Sputnik Planum through the 2- to 5-mile (3- to 8- kilometer) wide valleys indicated by the red arrows. The flow front of the ice moving into Sputnik Planum is outlined by the blue arrows. The origin of the ridges and pits on the right side of the image remains uncertain. (Photo via NASA/JHUAPL/SwRI)

Intricate Valley Glaciers on Pluto: This image covers the same region as the image before, but is re-projected from the oblique, backlit view shown in the new crescent image of Pluto. The backlighting highlights the intricate flow lines on the glaciers. The flow front of the ice moving into the informally named Sputnik Planum is outlined by the blue arrows. The origin of the ridges and pits on the right side of the image remains uncertain. This image is 390 miles (630 kilometers) across. (Photo via NASA/JHUAPL/SwRI)

This synthetic perspective view of Pluto, based on the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft, shows what you would see if you were approximately 1,100 miles (1,800 kilometers) above Pluto’s equatorial area, looking northeast over the dark, cratered, informally named Cthulhu Regio toward the bright, smooth, expanse of icy plains informally called Sputnik Planum. The entire expanse of terrain seen in this image is 1,100 miles (1,800 kilometers) across. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Mosaic of high-resolution images of Pluto, sent back from NASA’s New Horizons spacecraft from Sept. 5 to 7, 2015. The image is dominated by the informally-named icy plain Sputnik Planum, the smooth, bright region across the center. This image also features a tremendous variety of other landscapes surrounding Sputnik. The smallest visible features are 0.5 miles (0.8 kilometers) in size, and the mosaic covers a region roughly 1,000 miles (1600 kilometers) wide. The image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

In the center of this 300-mile (470-kilometer) wide image of Pluto from NASA’s New Horizons spacecraft is a large region of jumbled, broken terrain on the northwestern edge of the vast, icy plain informally called Sputnik Planum, to the right. The smallest visible features are 0.5 miles (0.8 kilometers) in size. This image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

This 220-mile (350-kilometer) wide view of Pluto from NASA’s New Horizons spacecraft illustrates the incredible diversity of surface reflectivities and geological landforms on the dwarf planet. The image includes dark, ancient heavily cratered terrain; bright, smooth geologically young terrain; assembled masses of mountains; and an enigmatic field of dark, aligned ridges that resemble dunes; its origin is under debate. The smallest visible features are 0.5 miles (0.8 kilometers) in size. This image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers).
(Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

This image of Pluto’s largest moon Charon, taken by NASA’s New Horizons spacecraft 10 hours before its closest approach to Pluto on July 14, 2015 from a distance of 290,000 miles (470,000 kilometers), is a recently downlinked, much higher quality version of a Charon image released on July 15. Charon, which is 750 miles (1,200 kilometers) in diameter, displays a surprisingly complex geological history, including tectonic fracturing; relatively smooth, fractured plains in the lower right; several enigmatic mountains surrounded by sunken terrain features on the right side; and heavily cratered regions in the center and upper left portion of the disk. There are also complex reflectivity patterns on Charon’s surface, including bright and dark crater rays, and the conspicuous dark north polar region at the top of the image. The smallest visible features are 2.9 miles 4.6 kilometers) in size. (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Two different versions of an image of Pluto’s haze layers, taken by New Horizons as it looked back at Pluto's dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto's north is at the top, and the sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto’s haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto’s disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth. (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

In this handout provided by the National Aeronautics and Space Administration (NASA), backlit by the sun, Pluto's atmosphere rings its silhouette like a luminous halo in this image taken by NASAs New Horizons spacecraft around midnight EDT on July 15, and released July 23, 2015. New Horizons passed by Pluto July 14, closing to a distance of about 7,800 miles (12,500 kilometers). This global portrait of the atmosphere was captured when the spacecraft was about 1.25 million miles (2 million kilometers) from Pluto and shows structures as small as 12 miles across The 1,050-pound piano sized probe was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida, (Photo by NASA/JHUAPL/SwRI via Getty Images)

Four images from New Horizons’ Long Range Reconnaissance Imager (LORRI) were combined with color data from the Ralph instrument to create this sharper global view of Pluto. (The lower right edge of Pluto in this view currently lacks high-resolution color coverage.) The images, taken when the spacecraft was 280,000 miles (450,000 kilometers) away from Pluto, show features as small as 1.4 miles (2.2 kilometers). That’s twice the resolution of the single-image view captured on July 13 and revealed at the approximate time of New Horizons’ July 14 closest approach. (Photo via NASA/JHUAPL/SwRI)

New Horizons scientists use enhanced color images to detect differences in the composition and texture of Pluto’s surface. When close-up images are combined with color data from the Ralph instrument, it paints a new and surprising portrait of the dwarf planet. The “heart of the heart,” Sputnik Planum, is suggestive of a source region of ices. The two bluish-white “lobes” that extend to the southwest and northeast of the “heart” may represent exotic ices being transported away from Sputnik Planum.

Four images from New Horizons’ Long Range Reconnaissance Imager (LORRI) were combined with color data from the Ralph instrument to create this enhanced color global view. The images, taken when the spacecraft was 280,000 miles (450,000 kilometers) away, show features as small as 1.4 miles (2.2 kilometers).

(Photo via NASA/JHUAPL/SwRI)

This new image taken July 14, 2015 shows an area on Pluto's largest moon Charon that has a captivating feature—a depression with a peak in the middle, shown here in the upper left corner of the inset.

The image shows an area approximately 240 miles (390 kilometers) from top to bottom, including few visible craters. “The most intriguing feature is a large mountain sitting in a moat,” said Jeff Moore with NASA’s Ames Research Center, Moffett Field, California, who leads New Horizons’ Geology, Geophysics and Imaging team. “This is a feature that has geologists stunned and stumped.”

This image gives a preview of what the surface of this large moon will look like in future close-ups from NASA's New Horizons spacecraft. This image is heavily compressed; sharper versions are anticipated when the full-fidelity data from New Horizons' Long Range Reconnaissance Imager (LORRI) are returned to Earth.

(Photo via NASA-JHUAPL-SwRI)

One of the final images taken before New Horizons made its closest approach to Pluto on July 14, 2015. (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

In this handout provided by NASA, a newly discovered mountain range lies near the southwestern margin of Pluto's Tombaugh Regio (Tombaugh Region), situated between bright, icy plains and dark, heavily-cratered terrain. This image was acquired by New Horizons Long Range Reconnaissance Imager (LORRI) on July 14, 2015 from a distance of 48,000 miles (77,000 kilometers) and sent back to Earth on July 20, 2015. Features as small as a half-mile (1 kilometer) across are visible.. The 1,050-pound piano sized probe was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida, (Photo by NASA/JHUAPL/SwRI via Getty Images)

This July 13, 2015, image of Pluto and Charon is presented in false colors to make differences in surface material and features easy to see. It was obtained by the Ralph instrument on NASA's New Horizons spacecraft, using three filters to obtain color information, which is exaggerated in the image. These are not the actual colors of Pluto and Charon, and the apparent distance between the two bodies has been reduced for this side-by-side view. (Photo via NASA/APL/SwRI)

In this handout provided by NASA, the dwarf planet Pluto (R) and Charon are shown July 11, 2015. NASA's New Horizons spacecraft is nearing its July 14 flyby when it will close to a distance of about 7,800 miles (12,500 kilometers). The 1,050-pound piano sized probe, which was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida, is traveling 30,800 mph as it approaches. (Photo by NASA/JHUAPL/SWRI via Getty Images)

Pluto’s bright, mysterious “heart” is rotating into view, ready for its close-up on close approach, in this image taken by New Horizons on July 12 from a distance of 1.6 million miles (2.5 million kilometers). It is the target of the highest-resolution images that will be taken during the spacecraft’s closest approach to Pluto on July 14. The intriguing “bulls-eye” feature at right is rotating out of view, and will not be seen in greater detail. (Photo via NASA/JHUAPL/SWRI)

In this handout provided by the NASA, the dwarf planet Pluto is shown at distance of about 2.5 million miles July 11, 2015. NASA's New Horizons spacecraft is nearing its July 14 flyby when it will close to a distance of about 7,800 miles (12,500 kilometers). The 1,050-pound piano sized probe, which was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida, is traveling 30,800 mph as it approaches. (Photo by NASA/JHUAPL/SWRI via Getty Images)

This map of Pluto, made from images taken by the LORRI instrument aboard New Horizons, shows a wide array of bright and dark markings of varying sizes and shapes. The elongated dark area informally known as “the whale,” along the equator on the left side of the map, is one of the darkest regions visible to New Horizons. It measures some 1,860 miles (3,000 kilometers) in length. Continuing to the right, along the equator, we see the four mysterious dark spots that have so intrigued the world, each of which is hundreds of miles across. Meanwhile, the whale’s “tail,” at the left end of the dark feature, cradles a bright donut-shaped feature about 200 miles (350 kilometers) across. (Photo viaNASA-JHUAPL-SWRI)

This series of New Horizons images of Pluto and its largest moon, Charon, was taken at 13 different times spanning 6.5 days, starting on April 12 and ending on April 18, 2015. During that time, the NASA spacecraft's distance from Pluto decreased from about 69 million miles (111 million kilometers) to 64 million miles (104 million kilometers). (Photo via NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

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Those images, chemical analyzes and other data show a complex, geologically active world 3 billion miles from Earth, with an underground ocean and volcanoes that appear to spew ice, five research papers published in this week's Science journal said.

"It's a pretty wild place geologically," said planetary scientist William McKinnon of Washington University in St. Louis, Missouri.

Another scientist described the diversity of landscapes as "astonishing."

How the varied terrain came to be remains a mystery for the distant Pluto, which has an average surface temperature of minus 380 degrees Fahrenheit (minus 229 degrees Celsius).

Scientists suspect several processes at work, including vaporization of volatile ices, such as nitrogen, carbon monoxide and methane, into Pluto's cold and unexpectedly compact atmosphere.

Though smaller than Earth's moon, Pluto likely still has enough internal heat from its formation some 4.5 billion years ago to help maintain its most prominent feature, a smooth, 620-mile (1,000-km) wide, heart-shaped basin known as Sputnik Planum.

Relatively young mountains west of Sputnik Planum and mounds to the south are harder to explain. Scientists suspect both rest on blocks of water ice, though how that came to exist on Pluto is unknown.

"We are puzzled by almost everything," said Alan Stern, the New Horizons mission's lead scientist.

The studies show that Pluto's primary moon, Charon, had an active life but ran out of naturally occurring radioactive heat in its rocks and froze through about 2 billion years ago.

Scientists now believe Charon and Pluto's four other small moons owe their existence to a crash between Pluto and another Pluto-sized body early in the solar system's history.

Similar to Earth's moon, scientists suspect Pluto's natural satellites were formed from the debris that was hurled into space after the crash.